The detergency of special electrolytic-reduction ion water (S-100) was evaluated in comparison with typical synthetic surfactants. Furthermore, to examine the cleaning mechanism of S-100, various physicochemical characteristics of S-100 were measured and a comprehensive evaluation of cleaning was performed. S-100 (10%) had a detergency comparable to that of various surfactants, such as sodium dodecyl sulfate and sodium dodecyl benzene sulfonate, which are generally blended or mixed in residential detergents. In addition, concentrated aqueous solutions of 10% or more of S-100 showed stronger detergency. The cleaning mechanism of S-100 is mainly attributed to the effect of surface tension reduction due to dissolved hydrogen or hydrogen nanobubbles in S-100, and the alkalinity generated by electrolysis charged the surface of the dirt or adherend, resulting in a peeling effect.